Internal combustion engines commonly have engine-driven alternators by which normal powered operation of the engine results in the generation of electricity that can be used both to charge a battery associated with the engine (e.g., the battery relied upon to start the engine) and also to power various electrical devices.
Notwithstanding the ubiquity of such engines equipped with alternators and the efficacy of using alternators in such engines, various problems continue to exist with the usage of such alternators. In particular, there can occur excessive voltage conditions or overvoltage transients that occur during operation of alternators, for example, due to transient conditions associated with alternator operation or arising from external sources (that is, sources other than the engines on which the alternators are operating). When such excessive voltage conditions occur, the excessive voltages that are applied to the battery and/or other electrical system components of the engine can disrupt operation of those devices and/or damage those devices. Indeed, adverse conditions such as an open line on a battery or due to improper grounding can provide alternator voltage to be applied directly to all existing electrical and electronic components connected to the shared power line. Such conditions can potentially lead to electrical damage as alternator voltage pulses provide a high repetitive energy not readily handled by other protection devices.
Although various techniques have been developed to minimize or eliminate the negative effects associated with such excessive voltage conditions, such existing techniques have corresponding disadvantages. In particular, shunting of charging current from alternator and shorting alternator terminals have been used to achieve over voltage protection and voltage regulation. Yet shorting out one or more stator windings of an alternator to achieve voltage regulation or to protect an electrical system from overvoltage conditions has several disadvantages. Alternator windings can overheat due to the short circuit conditions, since under those operational conditions large amounts of current flow through the alternator windings can occur. Voltage regulation using the shunting principle takes out the excess alternator current to common ground which may cause over heating of electronic components, and can necessitate a redesign to handle the additional load and heating. Another disadvantage is that the AC signal from the alternator can be lost during this regulation process due to shorting of the alternator terminals. In many applications alternator AC signal provides energy to loads like headlights, hand warmers and works as source of pulse for a tachometer circuit, and thus the loss of the AC signal from the alternator can preclude or limit desired operation of such electrical devices.
For at least these reasons, therefore, it would be advantageous if an improved system (or apparatus or device) and/or method for providing overvoltage protection with respect to batteries and/or other electrical components associated with engines having engine-driven alternators could be developed that avoided one or more of the disadvantages associated with conventional systems and methods such as those mentioned above and/or provided one or more other benefits.